(The Root) -- Torrence Hatch, the Baton Rouge, La., rapper better known to fans as Lil Boosie, faced the trial of his life in May. Charged with first-degree murder in the 2009 shooting death of Terry Boyd, Boosie stood accused of paying his friend Mike "Marlo Mike" Loudon $2,800 to carry out the hit. A conviction would have put him behind bars for good.

But local prosecutors had very little with which to work. With no physical evidence tying Boosie to the crime, they built their case on a prior confession from Marlo Mike -- a statement he later recanted at trial -- and, more important, Boosie's rap lyrics. Despite objections from defense attorneys, District Judge Mike Erwin allowed prosecutors to present lyrics from the songs "187" and "Bodybag," which they claimed provided evidence of Boosie's involvement in the murder. Fortunately for Boosie, the jurors were not convinced. After just an hour of deliberations, they found him not guilty in a unanimous decision.

Boosie may have escaped conviction, but the lingering issue raised by his case is the increasing use of rap lyrics at criminal trials across the country. Rather than treat rap music as an art form whose primary purpose is to entertain, prosecutors have become adept at convincing judges and juries alike that the lyrics are, in fact, either autobiographical confessions of illegal behavior or evidence of a defendant's propensity toward criminality. Defense attorneys can (and usually do) object, but the presiding judge, who has ultimate discretion in these matters, often allows them anyway.

According to Andrea Dennis, an associate professor at the University of Georgia School of Law who has written about rap lyrics in criminal trials, this gives government prosecutors a powerful advantage. "When courts permit the prosecutor to admit rap music lyrics as criminal evidence, they allow the government to obtain a stranglehold on the case," Dennis wrote in a 2007 journal article titled "Poetic (In)Justice? Rap Music Lyrics as Art, Life, and Criminal Evidence."

It is not exactly surprising that rappers find their lyrics used against them in this way. For years they have been vilified by critics who claim that rap and criminality go hand in hand. This is thanks in large part to lyrics that glorify illegal behavior, but also to the long list of performers who have served time in jail, effectively blurring the line between art and reality.

When they end up in court, this blurred line sometimes comes back to haunt them, and as a result, many rappers over the last two decades -- including well-known artists Mac Dre, Snoop Dogg and Beanie Sigel -- have seen their lyrics used against them in criminal proceedings. In the last several years, though, the practice has become widespread, with many cases involving amateur rappers who, imitating the conventions of commercially successful "gangsta" rap, attempt to project a criminal persona. When juries hear their lyrics, these rappers are often far less fortunate than Boosie.

Take, as a recent example, Clyde Smith (aka "G-Red" or "Tattoo Face"), also from Louisiana. In December of 2010, Smith and three other people were pulled over when Smith was allegedly clocked going 19 mph over the speed limit. When he couldn't produce a driver's license, police searched his car and found him with the prescriptions drugs hydrocodone, Xanax and Soma, which he had purchased in neighboring Texas. Despite the fact that he had prescriptions for all of the drugs, that no pills were missing from any of the containers and that he had a documented medical condition that justified his use of the drugs, he was charged with possession with intent to distribute.

At trial the following May, the judge overruled vigorous objections from defense counsel and allowed the prosecutor to show the jury two YouTube videos. In one, a video for a song called "B.M.F. Freestyle," Smith raps, "Another trip to Texas ... we going doctor shopping." In another video, called "Behind-the-Scenes," Smith -- still in character as G-Red, but talking instead of rapping -- insists to the camera that "We really do the sh-- that we rap about. Like, we really take those trips." Although he took the stand and repeatedly claimed that his raps were fiction and intended to entertain, the predominantly white jury had seen all it needed.

Smith was found guilty and, because he had a prior record, was sentenced to a jaw-dropping 30 years in prison. According to Carolyn McNabb, his attorney, the rap lyrics were "the primary motivator for the guilty verdict." Despite having a very strong defense, she knew that the YouTube videos were going to seal the outcome. "I knew when the jury saw them, it was over," she said. "That's why I fought so hard to keep them out."

Five months later, aspiring rapper Olutosin Oduwole also found himself on trial and facing jail time for his lyrics. In July 2007, Oduwole's car ran out of gas, forcing him to abandon it on the Edwardsville campus of Southern Illinois University, where he was a student. When school authorities found the car, they also found a crumpled piece of paper stuffed between the seats on which Oduwole had made written reference to a PayPal account and included the lines, "If this account doesn't reach $50,000 in the next 7 days then a murderous rampage similar to the VT shooting will occur at another highly populated university. THIS IS NOT A JOKE!"

Police immediately searched Oduwole's apartment, where they found a legally acquired handgun. They also learned that he had been trying to purchase additional guns, also legally, and that was all they needed. Oduwole was charged with attempting to communicate a terrorist threat.

At the October 2011 trial, defense attorneys argued that Oduwole was an amateur rapper who took compulsive notes about ideas for his lyrics. They even brought in an expert witness who reviewed Oduwole's other notebooks of lyrics and compared them with the note.

She testified that the writings on the crumpled note were clearly an idea for a rap song or "the formative stages of a rap lyric." She also testified that Oduwole was an aspiring "gangsta" rapper and that his lyrics comported with what one might expect from someone in that subgenre. Nevertheless, the all-white jury convicted the 26-year-old Oduwole, who is black, and he was later sentenced to five years in prison.

However, even casual fans understand that exaggeration and hyperbole are hallmarks of the genre. Rappers are putting on an act, even if it's one that in some ways mirrors their reality. Their use of alternate names ought to make this obvious.

"Most rappers use a stage name or something other than their 'government name' when performing," Todd Boyd, professor of critical studies at the University of Southern California, told The Root. "This suggests that they are characters with a persona."

And sometimes that persona is a far cry from the person behind it. Rick Ross, one of the most popular rappers today, uses his lyrics to portray a criminal lifestyle patterned after the real Rick Ross, a notorious Los Angeles gangster. The rapper -- whose real name is William Leonard Roberts II -- is no brazen criminal himself, though. In one of life's delightful ironies, it turns out that he once worked as a prison guard.

But focusing on a Rick Ross persona, or one like it, gives prosecutors a powerful tool at trial, especially when their cases are weak. And this, argues Andrea Dennis, is a reason to exclude rap lyrics altogether. "I tend to favor exclusion," she told The Root, "because of reliability and prejudice concerns that may result in conviction despite insufficient other evidence."

Although jurors are supposed to acquit when there's reasonable doubt, the weight of lyrics can be too great, particularly if those lyrics reinforce preconceived notions about the defendant. Indeed, as Boyd reminds us, in these trials authorities are often prosecuting someone "who already looms as a threatening stereotype in the minds of society."

Using lyrics, then, isn't just a matter of an art form being sacrificed for the sake of an easy conviction; it can also be a pernicious tactic that plays upon and perpetuates enduring stereotypes about the inherent criminality of young black men.

These same stereotypes make it difficult for many people to regard rap as a legitimate art form in the first place. According to Paul Butler, professor of law at Georgetown University (and a former prosecutor himself), "Some people have always had a hard time conceptualizing the young black men who are the primary creators of hip-hop as artists."

For Butler, this helps explain why rap lyrics are so frequently introduced. But it also reveals a glaring double standard. "Using lyrics as evidence against hip-hop artists is as preposterous as bringing organized crime charges against the author of The Godfather or gang charges against the director of Scarface," he says. "It's art, stupid."

Erik Nielson is assistant professor of liberal arts at the University of Richmond. His research focuses on African-American literature and hip-hop culture.

Correction: A previous version of this story identified Paul Butler as a George Washington University professor. He joined the faculty of Georgetown Law this week. We regret the error.